To stimulate the growth of tobacco leaves, farmers customarily remove the flowers, stem apex, and some top leaves of immature tobacco plants. This process is known as "topping". Topped tobacco plants have a tendency to grow axillary buds ("tobacco suckers") which consume energy otherwise available for the development of tobacco leaves. In order to produce high quality leaves, tobacco plants are desuckered, using manual means or with the aid of plant growth regulation agents. Most tobacco plants in the U.S. are desuckered using maleic hydrazide.
Maleic hydrazide has some undesirable characteristics. Its use can undesirably flavor tobacco leaves, reduce their size, increase their reducing sugar content, imbalance their moisture content, and promote false ripening (premature yellowing) of the leaves. These problems become more severe when maleic hydrazide is applied frequently or at high application rates. for these reasons, it would be very desirable if tobacco desuckering could be carried out using other plant growth regulation agents, or using reduced frequency of application and/or amounts of maleic hydrazide.
Surfactants have long been used to enhance the efficacy of plant growth regulator formulations. Surfactants may provide enhanced penetration, wetting, or sticking characteristics in formulations containing surfactant and plant growth regulator, or assist in dissolving plant growth regulators in carriers such as water or oil. Some surfactants are often themselves plant growth regulation agents which act by contact or systemic action. In general, the mechanism of action of formulations containing surfactants in plants, and the manner of optimizing the choice of surfactant for use with a particular plant species, plant growth regulator, and desired plant growth regulation effect, is not well understood.
A variety of surface-active agents (i.e., surfactants) derived from fatty acids, fatty alcohols, and esters and polyethoxylated condensate products thereof have been used as adjuvants in herbicidal or plant growth regulator formulations. For example, C.sub.5-22 aliphatic carboxylic acids have been used to increase the solubility of a proton acceptor amino medicament or herbicide in oil in U.S. Pat. No. 3,172,816. Polyunsaturated linoleic or linolenic acids are combined with the grass herbicide "Barban" to combat wild oats in U.S. Pat. No. 4,134,754. Also, C.sub.6-18 saturated fatty alcohols are combined with isopropyl-N-(3-chlorophenyl)carbamate to provide a composition for inhibiting tobacco sucker development in U.S. Pat. No. 3,438,765. U.S. Pat. No. Re 30216 describes a mixture of C.sub.6-18 saturated fatty alcohols and maleic hydrazide derivatives for tobacco sucker control, the resulting compositions also optionally containing reaction products of ethylene oxide with saturated long chain fatty acids as surface-active agents. Methyl esters of C.sub.6-12 saturated fatty acids are mixed with fatty acid esters of polyethoxylated sorbitan (wherein the fatty acid contains about 10 to about 18 carbon atoms and wherein there are about 5 to about 80 ethoxy moieties per molecule) to provide chemical pinching agents in U.S. Pat. No. 3,620,712. Lower alkyl esters of saturated and unsaturated C.sub.6-18 fatty acids are mixed with isopropyl-N-(3-chlorophenyl)carbamate to provide tobacco desuckering compositions in U.S. Pat. Nos. 3,326,664 and 3,340,040, and are used alone and in combination with isopropyl-N-(3-chlorophenyl)carbamate as tobacco desuckering compositions in Tso et al, "Inhibition of Tobacco Axillary Bud Growth with Fatty Acid Methyl Esters", J. Agr. Food Chem., 13, 78 (1965). Condensates of ethylene oxides and various alcohols have been used in herbicide formulations, for example, in U.S. Pat. Nos. 3,990,884 (lauryl alcohol), 3,954,439 (nonyl phenol), and 4,084,956 (various saturated fatty alcohols, and oleyl alcohol, in combination with the grass herbicide "Barban").
Various surface active agents containing condensates of ethylene oxide and unsaturated fatty acids have been used in non-agricultural applications, for example, as anti-caking agents in cosmetics. Also, polyethoxylated C.sub.12-26 saturated and unsaturated fatty acid esters have been reported for use as anti-caking and wetting agents in pesticidal formulations containing the non-herbicidally active compound 2-heptadecyl-2-imidazoline, in U.S. Pat. No. 3,100,174.
Despite all of the above reported combinations of herbicides or plant growth regulators (e.g., tobacco desuckering agents) with saturated or unsaturated fatty acids, fatty alcohols, and esters and ethylene oxide condensates thereof, and the above-described combination of the pesticide 2-heptadecyl-2-imidazoline with polyethoxylated unsaturated fatty acid esters, no tobacco desuckering or other plant growth regulation formulations containing condensates of ethylene oxide and unsaturated fatty acids have been previously reported. Also, no tobacco desuckering or other plant growth regulation formulations containing condensates of ethylene oxide and unsaturated fatty amines, unsaturated fatty amides, or unsaturated fatty alcohols have been reported.